Clad Nd:YAG fibers for laser applications

We report the implementation of an extrusion method to clad Nd:YAG single crystal fibers with index-matched glasses (
\Deltan = 0.048
). A propagation loss coefficient of 0.08 dB/cm was measured for the fundamental mode of a 41-μm-diameter glass-clad fiber laser, an improvement of about one order of magnitude over unclad fibers. Guided clad fiber lasers operated at 1.064 μm with thresholds as low as 0.3-0.5 mW and up to 65-mW CW output power are also reported. The origins of and means of reducing the residual loss are discussed.